14,092 research outputs found
The Elderly and Health Care Rationing
[Excerpt] “The allocation of health care resources involves a societal determination of what resources should be devoted to a particular program. The allocation process is typically performed on a ―macro‖ level, with allocation decisions often affecting only statistical lives. In contrast to the identifiable lives often affected by health care rationing, statistical lives affected by allocation decisions are much more readily sacrificed. A common means of deciding health care allocation is through political processes. Government decisions pertaining to health care spending and regulation typically involve allocation determinations. For example, the Medicare and Medicaid programs allocate resources for numerous purposes. Hospitals, too, regularly make allocation decisions in determining the quantity and type of resources to have available. Their actions, in turn, impact directly upon physicians who subsequently also become health care allocators.
Anthropomorphic teleoperation: Controlling remote manipulators with the DataGlove
A two phase effort was conducted to assess the capabilities and limitations of the DataGlove, a lightweight glove input device that can output signals in real-time based on hand shape, orientation, and movement. The first phase was a period for system integration, checkout, and familiarization in a virtual environment. The second phase was a formal experiment using the DataGlove as input device to control the protoflight manipulator arm (PFMA) - a large telerobotic arm with an 8-ft reach. The first phase was used to explore and understand how the DataGlove functions in a virtual environment, build a virtual PFMA, and consider and select a reasonable teleoperation control methodology. Twelve volunteers (six males and six females) participated in a 2 x 3 (x 2) full-factorial formal experiment using the DataGlove to control the PFMA in a simple retraction, slewing, and insertion task. Two within-subjects variables, time delay (0, 1, and 2 seconds) and PFMA wrist flexibility (rigid/flexible), were manipulated. Gender served as a blocking variable. A main effect of time delay was found for slewing and total task times. Correlations among questionnaire responses, and between questionnaire responses and session mean scores and gender were computed. The experimental data were also compared with data collected in another study that used a six degree-of-freedom handcontroller to control the PFMA in the same task. It was concluded that the DataGlove is a legitimate teleoperations input device that provides a natural, intuitive user interface. From an operational point of view, it compares favorably with other 'standard' telerobotic input devices and should be considered in future trades in teleoperation systems' designs
Investigation and modeling of space shuttle main engine shutdown transient chugging
The space shuttle main engines experience a low frequency pressure pulsation in both the fuel and oxidizer preburners during the shutdown transient. This pressure pulsation, called chugging, has been linked to undesirable bearing loads and possible damage to the spark ignitor supply piping for the fuel preburner. The problem is briefly described and a model is proposed that includes: (1) a transient stirred tank reactor model for the combustion chamber, (2) a resistance capacitance model for the supply piping and (3) purge gas/liquid oxygen interface tracking
Embedded minimal surfaces
The study of embedded minimal surfaces in \RR^3 is a classical problem,
dating to the mid 1700's, and many people have made key contributions. We will
survey a few recent advances, focusing on joint work with Tobias H. Colding of
MIT and Courant, and taking the opportunity to focus on results that have not
been highlighted elsewhere.Comment: To appear in proceedings of Madrid ICM200
Optimal bounds for ancient caloric functions
For any manifold with polynomial volume growth, we show: The dimension of the
space of ancient caloric functions with polynomial growth is bounded by the
degree of growth times the dimension of harmonic functions with the same
growth. As a consequence, we get a sharp bound for the dimension of ancient
caloric functions on any space where Yau's 1974 conjecture about polynomial
growth harmonic functions holds.Comment: A stronger sharp dimension bound is added which is an equality on
Euclidean space. To appear in Duke Math. Journa
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